Natural waters may contain viruses, which pose a risk if water is used as raw water for drinking water or for recreational purposes. Norovirus is one of the most common causative agents for waterborne gastroenteritis infections due to its stability in the environment and due to a low infectivity dose needed to cause infection. For several years, evidence has been collected that suggests that levels of present bacterial indicators and noroviruses don’t correlate, and better alternatives for indicators are searched for.
One-year survey of the presence of noroviruses in river water used for secondary water source as well as treated wastewater taken from treatment plants along the river was conducted by researchers at the University of Helsinki, Helsinki region environment services authority and the water protection association of the river Vantaa and Helsinki region. Later, the monitoring was continued for some winter-spring months for norovirus and adenovirus. Viral nucleic acids were detected using molecular methods, such as real-time reverse transcription-polymerase chain reaction.